Nonlinear deformations of a cylindrical pipe with pre-stressed thin coatings

The paper presents an exact solution for the problem of large deformations of torsion, axial tension–compression, and radial expansion or shrinkage of an elastic hollow circular cylinder equipped with pre-stressed elastic coatings. Surface coatings are modeled using the six-parameter nonlinear shell theory. The constitutive material of the cylinder is described by a three-dimensional nonlinear model of the isotropic incompressible body of the general form. Special boundary conditions describe the interaction of this material with thin coatings on the inner and outer surface of the pipe. Based on the solution obtained, numerical calculations were performed on the effect of preliminary stresses in coatings on the stress–strain state of a cylindrical pipe.

Создание равномерных покрытий импульсным лазерным осаждением

The present paper deals with the selection of laser beam processing parameters that guarantee the formation of thin coatings with even thickness by means of the laser beam deposition. Laser deposition was carried out in the atmosphere of Ar and Si and SiC samples were used as a source for the deposited material. Preliminary experiments show that there is a direct dependency between the brightness of the image of the deposited layer (at uniform illumination conditions) and its thickness. Therefore, it was possible to determine the thickness of the deposited layer for various processing parameters and to calculate the laws of motion of the work piece that guarantee the deposition of the layer with a minimal deviation of thickness from the required value. Calculated parameters were successfully used for the deposition of coatings on a substrate of a relatively large area.

Metrological provision of measurement using NanoScan-3D microscopenanothercomer

A review of methods and instrumentation for the study of tribological and mechanical properties of the surface. It is established that the most common methods for studying these properties in the micro and nano-ranges are contact methods based on the interaction of the hard tip with the material under study. In scanning probe microscopy, a bimorph piezoceramic probe with a diamond tip is the main element of the measurement modules used for nanoindentation and sclerometry to comprehensively study the tribological and mechanical properties of the surface. The original design of the sensor allows to implement more than ten measuring techniques on one device. The operation of these devices in the semi-contact scanning probe-microscopic mode allows to obtain images of the surface relief and a map of the distribution of elastic properties. The indentation mode allows to measure hardness and modulus of elasticity, to estimate elastic recovery of material after indentation. The method allows to determine the abrasion resistance and hardness of the material, adhesion and thickness of thin coatings.